Sugar alcohol split injection conversion

ABSTRACT

A method of hydrotreating liquefied biomass feedstock with diesel feedstock to produce alkanes is demonstrated that prevents damage to the reactor catalyst, reduces coke production, and converts nearly all of the polyols to alkanes. In order to mitigate the potential coking issue and to moderate the temperature of the catalyst bed while maintaining high conversion for sugar alcohol to hydrocarbon via a hydrotreating process, a diesel feedstock is fed over the reactor catalyst with multiple injections of polyol feedstock along the reactor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application which claims benefitunder 35 USC §119(e) to U.S. Provisional Application Ser. No. 61/250,633filed Oct. 12, 2009, entitled “SUGAR ALCOHOL SPLIT INJECTIONCONVERSION,” which is incorporated herein in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

None.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to methods and apparatus forsugar alcohol split injection method to mitigate the potential cokingissue and to moderate the temperature of the catalyst bed whilemaintaining high conversion for sugar alcohol to hydrocarbon via ahydrotreating process. In this method, the sugar alcohol stream is splitto several streams and injected along the catalyst bed while dieseldiluent is injected into the reactor at the top of the catalyst bed.

BACKGROUND OF THE DISCLOSURE

Processes to convert renewable resources into transportation fuelsusually involve several steps. For example, one approach is to use acidsto convert carbohydrates, starches, lignins, and other biomass intosugars such as glucose, lactose, fructose, sucrose, dextrose. Thecatalytic hydrogenation of the carbonyl groups of a sugar like glucose(C₆H₁₂O₆) can then produce a polyalcohol including sorbitol (C₆H₁₄O₆).

There has been a significant effort to produce alkanes through catalyticconversion of aqueous sorbitol and other bio-generated polyols. Chen andKoenig, U.S. Pat. No. 4,503,278, convert carbohydrates such as starch,cellulose and sugar on a crystalline silicate zeolite catalyst intofuels and useful chemicals by increasing hydrocarbon size. In U.S. Pat.No. 5,959,167, Shabtai and associates use lignins in a two-stagecatalytic reaction process to produce a reformulated hydrocarbongasoline product. In US2009126260, Aravanis, et al., convert terpenesfrom biomass through catalytic cracking to generate suitable fuelproducts. Gruter, EP2034005, prepares a hydroxymethylfurfural fueladditive from biomass by dehydration with an acid catalyst. InWO2008114033, Fredriksen and Myrstad, mix bio-oil and mineral oil in anFCC cracking unit to generate bio-LPG, bio-naphtha and alkylating orcatalytically polymerizing bio-LPG fraction to form a bio-gasoline.Dumesic et al., U.S. Pat. No. 7,572,925, convert sugars to furanderivatives (e.g. 5-hydroxymethylfurfural, furfural, dimethylfuran,etc.) using a biphasic reactor containing a reactive aqueous phase andan organic extracting phase. Finally in US2008173570, Marchand andBertoncini use hydrodesulphurization of an incoming stream that issubsequently cut with plant and/or animal oils, the oil mixture ishydrotreated with specialized equipment to effluents with higher cetaneratings. Unfortunately these systems do not address current problemsencountered with processing biomass to automotive fuels.

Some advances have been made toward the catalytic conversion of sorbitolto alkanes. Huber, et al., (2004) used Palladium, Silica, and Aluminacatalysts to convert sorbitol to a stream of alkanes including butane,pentane, and hexane. Incorporating hydrogenation of reactionintermediates with produced hydrogen increased yield. David, et al.(2004) assayed conditions for the production of hydrogen and/or alkanesfrom renewable feeds including aqueous solutions of sorbitol. In areview, Metzger (2006) notes alkane production from aqueous phasesorbitol reforming is improved with a bi-functional catalyst including ametal (Pt, Pd, or the like) and acid including silica alumina with theco-production of H₂ and CO₂. Although the yield of alkanes could beincreased up to 98% when hydrogen was co-fed with the aqueous sorbitolstream they were able to reduce CO₂ production, increasing H₂Oproduction and pathway efficiency.

Previous methods are limited by size, temperature, products, andconversion rates. Unfortunately at higher temperatures and highercatalytic activity, these reactions become quickly fouled. The catalystmust be removed and replaced before sufficient volumes of fuel areprocessed. Thus, these reactions must be improved to meet a commercialproduction scale and cost effectiveness. The processes above do notremove oxygen, require expensive catalysts, are subject to fouling, andare not scalable to production levels required. Additionally, processingbiomass as a common feedstock is hindered by short catalyst lifetime,increased pressures and temperatures, increased production of cokebyproducts, and increased corrosiveness. These undesirable side-effectshinder mass production of renewable fuels from biomass. Although noblemetals have been used for hydrotreating at lower temperatures, theseexpensive catalysts do not alleviate the problem of fouling and thereactions are difficult to perform on a commercial scale. A method ofconverting large quantities of biomass is required that does not damagecatalysts and equipment during the refining process.

BRIEF DESCRIPTION OF THE DISCLOSURE

A method of hydrotreating liquefied biomass feedstock with dieselfeedstock to produce alkanes is demonstrated that prevents damage to thereactor catalyst, reduces coke production, and converts nearly all ofthe polyols to alkanes. In order to mitigate the potential coking issueand to moderate the temperature of the catalyst bed while maintaininghigh conversion for sugar alcohol to hydrocarbon via a hydrotreatingprocess, a diesel feedstock is fed over the reactor catalyst withmultiple injections of polyol feedstock along the reactor.

Hydrotreating a mixture of sorbitol and diesel over a commercialhydrotreating catalyst produces lighter alkanes and hexanes desirablefor gasoline fuels. Additionally, these methods can be modified toincrease production of high octane methyl-cyclopentane (MCP) instead ofn-hexane (HEX). Production of MCP dramatically increases the octanevalue of the product, thus commercial quantities of sorbitol areconverted to hydrocarbons that can be blended directly into a valuablegasoline stream.

“Catalysts” as described herein are commercial grade hydrotreatingcatalysts used by petroleum industries in refining processes. Mostmetals catalyze hydrotreating including transition metals such ascobalt, molybdenum, nickel, titanium, tungsten, zinc, antimony, bismuth,cerium, vanadium, niobium, tantalum, chromium, manganese, rhenium, iron,cobalt, and the noble metals including platinum, iridium, palladium,osmium, rhodium and ruthenium (Chianelli, 2002) along with other metalcompounds. Binary combinations of cobalt and molybdenum, nickel andmolybdenum, and nickel and tungsten are also highly active. Commercialgrade catalysts include Cobalt-Molybdenum (Co/Mo), Nickel-Molybdenum(Ni/Mo), Titanium-Molybdenum (Ti/Mo), Nickel-Tungsten (Ni/W), Cobalt(Co), Molybdenum (Mo), Copper (Cu), Iron (Fe), combinations thereof andother commercially available hydrotreating catalysts. Noble metalcatalysts, including Platinum (Pt), Palladium (Pd), and Ruthenium (Ru)catalysts may also be used. One of ordinary skill in the art may selecta catalyst based on composition, structure and charge to achievespecific activity from the catalyst. Although selection of a catalystand activity is highly predictable because the reaction is based on thesurface structure of the catalyst, the rate of reaction and overallproductivity may vary dependent upon the reactants, reaction conditions,and flow rate.

Commercial refining catalysts are readily available from a variety ofsources including ALBEMARLE, ADVANCED REFINING TECHNOLOGIES (ART),AMERICAN ELEMENTS , EURECAT, FISCHER, HALDOR TOPSOE, HEADWATER, PGMCATALYSTS & CHEMICALS, SIGMA, and other chemical suppliers. Catalystsare supported on an alumina, silica, titania, zeolite, carbon or othersupport materials. Catalysts may be microsized, nanosized, fluidized orother catalyst forms dependent upon the reactor size, shape andconditions under which the reaction is run. The catalysts may also beunsupported including unsupported Co/Mo, Co/W, Ni/Mo, Ni/W, Ti/Mo, Ti/W,Co/Mo/W, Ni/Mo/W, Ti/Mo/W and the like are used for hydrotreatingpolyols to yield increased hexanes, pentanes, cyclopentanes and otherhigher octane products. In one embodiment a Co/Mo catalyst on aluminasupport is used in mixed bed reactors. In another embodiment, a Ni/Mocatalyst on a solid alumina support is used for continuous flow throughreactions. Additionally, a Co/Mo catalyst on a zeolite support may beused. In a preferred embodiment, unsupported Ni/Mo, Co/Mo, orcombinations of Ni/Mo and Co/Mo catalysts are used in a commercialrefinery to process mixed polyols.

Fuel oil feedstocks include a variety of fuels including fuels in thediesel boiling range. Additionally other fuel feedstocks may be used forprocessing including jet fuel, kerosene, diesel fuel, heating oil, andfuel oils. Diesel fuels include petro-diesel, bio-diesel, syntheticdiesel, blended diesel, and the like. Market price and availability areused to determine the fuel feedstock of choice. Typically the fuel withthe lowest overall cost including direct cost, transportation, processmodification, processing and any other costs that may be associated withthe fuel oil feedstock.

Polyol feedstocks consist of one or more polyols in an aqueous solution.Polyols include glycerol, sorbitol, xylitol, and the like. Liquefactionof biomass typically produces feedstocks containing sorbitol andxylitol. Feedstocks may contain from about 50 to about 98% v/v polyol.In one embodiment a polyol feedstock contains approximately 30%, 35%,40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, up to 98%sorbitol, xylitol and mixtures of sorbitol and xylitol. Althoughsorbitol feedstock comprises sorbitol and aqueous solution, additionalpolyols, oils, and sugars are present after liquefaction. Many isomers,polymers, and soluble sugars are present in the aqueous liquefactionfraction. Hydrotreating will convert many of these to valuable fuelproducts (Table 1).

TABLE 1 POLYOLS AND THEIR PRODUCTS. Polyol Carbons Oxygens ProductGlycol 2 2 Ethane Glycerol 3 3 Propane Erythritol 4 4 Butane Threitol 44 Butane Arabitol 5 5 Pentane Ribitol 5 5 Pentane Xylitol 5 5 PentaneAllitol 6 6 Hexane Dulcitol 6 6 Hexane Galactitol 6 6 Hexane Iditol 6 6Hexane Mannitol 6 6 Hexane Sorbitol 6 6 Hexane Isomalt 12 11 HexaneLactitol 12 11 Hexane Maltitol 12 11 Hexane Trehalose 12 11 Hexane

Light gasses include methane, ethane, butane, isobutane, propane,pentane and mixtures thereof. Light gases produced during hydrotreatingmay be processed into individual or mixed products such as methane,ethane, propane, butane, compressed natural gas (CNG), natural gasliquids (NGL), liquefied petroleum gas (LPG), liquefied natural gas(LNG), or transferred to reforming for hydrogen generation with biomasssolids.

A hydrotreating reactor is described where the hydrotreating reactor hasa hydrotreating catalyst; a diesel feedstock injector at the beginningof the reactor catalyst, a polyol feedstock injector at or near thebeginning of the reactor catalyst, and one or more additional polyolfeedstock injectors at intervals along the reactor catalyst.

A method of hydrotreating polyol feedstocks to alkanes is describedwhere a diesel feedstock is injected on the hydrotreating catalyst atthe beginning of the reactor catalyst, a polyol feedstock is injected onthe hydrotreating catalyst at or near the beginning of the reactorcatalyst, and one or more additional polyol feedstocks are injected onthe hydrotreating catalyst at intervals along the reactor catalyst.

Biomass is hydrotreated by generating a liquefying biomass to generate apolyol feedstock, contacting a hydrotreating catalyst with a fuel oilfeedstock at the beginning of the reactor catalyst, contacting thehydrotreating catalyst with the polyol feedstock at or near thebeginning of the reactor catalyst, and contacting the hydrotreatingcatalyst with one or more additional polyol feedstocks at intervalsalong the reactor catalyst, thus generating alkanes.

Polyol feedstocks are typically mixtures of Glycol, Glycerol,Erythritol, Threitol, Arabitol, Ribitol, Xylitol, Allitol, Dulcitol,Galactitol, Iditol, Mannitol, Sorbitol, Isomalt, Lactitol, Maltitol,Trehalose, and other products of the liquefaction process.

Fuel oil feedstocks include gasoline, jet fuel, kerosene, heating oil,fuel oils, diesel fuel, petro-diesel, bio-diesel, synthetic diesel,blended diesel, and combinations thereof. The fuel oil feedstock may beheated to reaction temperature prior to contacting the hydrotreatingcatalyst.

Hydrotreating catalyst are commonly metallic catalysts including cobalt(Co), molybdenum (Mo), nickel (Ni), titanium (Ti), tungsten (W), zinc(Zn), antimony (Sb), bismuth (Bi), cerium (Ce), vanadium (V), niobium(Nb), tantalum (Ta), chromium (Cr), manganese (Mn), rhenium (Re), iron(Fe), platinum (Pt), iridium (Ir), palladium (Pd), osmium (Os), rhodium(Rh), and ruthenium (Ru). Hydrotreating catalysts are also available asbimetallic catalysts including Co/Mo, Co/W, Ni/Mo, Ni/W, Ti/Mo, or Ti/W.Unsupported catalysts are commercially available as Co/Mo, Co/W, Ni/Mo,Ni/W, Ti/Mo, Ti/W, Co/Mo/W, Ni/Mo/W, Ti/Mo/W. These catalysts may beused alone or in a variety of mixed bed reactors.

Approximate reaction temperatures range from about 400° F., 425° F.,450° F., 475° F., 500° F., 525° F., 550° F., 575° F., 600° F., 625° F.,650° F., 675° F., 700° F., 725° F., 750° F., 775° F., 800° F., 825° F.,850° F., 875° F., to 900° F. or greater. Reaction temperatures may varyacross the reactor by up to 25° F.

The reaction pressures ranges from of 500, 550, 600, 650, 700, 750, 800,850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1500, 1750, 2000,2250, 2500, 2750, to 3000 psig or greater.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and benefitsthereof may be acquired by referring to the follow description taken inconjunction with the accompanying drawings in which:

FIG. 1: Hydrotreating process for sugar alcohols to hydrocarbons.

FIG. 2: Reactor configuration.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Turning now to the detailed description of the preferred arrangement orarrangements of the present invention, it should be understood that theinventive features and concepts may be manifested in other arrangementsand that the scope of the invention is not limited to the embodimentsdescribed or illustrated. The scope of the invention is intended only tobe limited by the scope of the claims that follow. The present inventionprovides a method to increase the amount of polyol processed in ahydrotreating reactor by providing multiple polyol feedstock injectorsalong the reactor catalyst.

U.S. Provisional Application Ser. No. 61/236,347 filed Aug. 24, 2009,entitled “Hydrotreating Carbohydrates,” which is incorporated herein inits entirety, describes a mixed sugar alcohol, diesel processing toconvert biomass to liquid hydrocarbon fuels. Cellulose and hemicelluloseare two major constituents in the biomass and can be broken down to C6and C5 sugars using acid or enzyme hydrolysis processes. C6 and C5sugars can be further hydrogenated to sugar alcohols using a commercialprocess. We have found that the sugar alcohols, such as sorbitol, can behydrogenated to C6 hydrocarbons using a hydrotreating process. However,high coking rate is an issue for such process due to the nature of sugaralcohol molecule.

The following examples of certain embodiments of the invention aregiven. Each example is provided by way of explanation of the invention,one of many embodiments of the invention, and the following examplesshould not be read to limit, or define, the scope of the invention.

MATERIALS & METHODS

Sorbitol feedstock was processed in the presence of diesel feedstock atbetween 400-1000° F. and between about 150 to about 3000 psi. Sorbitolfeedstock contains approximately 70% v/v sorbitol in aqueous solution.Sorbitol feedstock may range from about 50 to about 100% v/v sorbitol. Atypical sorbitol solution often contains between 30 and 80% v/v sorbitoland many sorbitol solution are approximately 30% v/v, 35% v/v, 40% v/v,45% v/v, 50% v/v, 55% v/v, 60% v/v, 65% v/v, 70% v/v, 75% v/v, 80% v/v,85% v/v, 90% v/v, or 95% v/v sorbitol. Pure sorbitol may also beprocessed, but because of the hygroscopic nature it is usually found atless than 98% v/v sorbitol unless dried. Because the sorbitol feedstockis the product of a variety of reactions often derived from biomass thefinal sorbitol concentrations are quite variable and additionalcompounds may be found in a sorbitol feedstock.

Diesel feedstock is a commonly a mixture of diesel range hydrocarbonproducts. Diesel may also be supplied through a variety of sourceseither within or delivered to the refinery. In one aspect, dieselproducts remaining after processing are recycled to the gasoline fuelproduction. Sulfur present in some diesel feeds is used to maintainhydrotreating catalyst activity. Diesel feedstocks commonly containbetween approximately 15 and 1500 ppm sulfur compounds. Sulfur contentmay get as high as 1% w/v for high sulfur diesels. For low sulfurdiesels, the diesel feed is spiked with a very small amount of mercaptanor other sulfur compounds. In one embodiment the diesel feed is spikedwith about 0.1 to about 1.0% w/v sulfur containing compound. In anotherembodiment the diesel feed is spiked with about 0.25 to about 0.5% w/vsulfur containing compound. In one embodiment the sulfur content israised to above 1000 ppm.

A variety of sulfur compositions may be used to increase sulfur contentof the diesel feedstock. Examples of sulfur compounds include, but arenot limited to, hydrogen sulfide, carbonyl sulfide (COS), carbondisulfide (CS₂), mercaptans (RSH), organic sulfides (R—S—R), organicdisulfides (R—S—S—R), thiophene, substituted thiophenes, organictrisulfides, organic tetrasulfides, organic polysulfides,benzothiophene, alkyl thiophenes, dibenzothiophene, alkylbenzothiophenes, alkyl dibenzothiophenes, and the like, and mixturesthereof as well as heavier molecular weights of the same, wherein each Rcan be an alkyl, cycloalkyl, or aryl group containing 1 to about 10carbon atoms. These include mercaptan, dimethyl sulfide, hydrogensulfide, dimethyl polysulfides, mercaptoethanol, mercaptobutanol,2-mercaptoethyl sulfide, mercaptopropanol, 3-mercapto-2 methyl propanol,mercaptopentanol, thioglycerine, dithiothreitol, and other sulfurcompositions may be used. Typically a sulfur composition is selectedbased on cost, quantity, availability, and chemical properties. In mostcases a more soluble sulfur compound is selected that makes sulfuravailable for catalytic activity. In some cases a less soluble compoundis used to maintain active sulfur compounds over a longer period oftime, for greater volumes, or under varying reaction conditions.

EXAMPLE 1 Catalyst Bed Injection

Experimental results, see U.S. Provisional Application 61/236,347 whichis incorporated herein in its entirety, suggested that hydrocarbondilution including using diesel as a diluent reduces the sugar alcoholcoking tendency (Table 3, determined based on the reactor pressure drop)while the increasing of the diesel to sugar alcohol ratio had verylittle impact on sugar alcohol conversion and product distribution(Table 2). In addition, it is observed that the majority of sorbitol tohydrocarbon conversion reaction is taking place at the top part of thecatalyst bed. The sugar alcohol hydrotreating unit is operated bysplitting sugar alcohol injection along the catalyst bed. By doing so,it keeps the high diesel to sorbitol dilution along the entire length ofthe catalyst bed while reducing the circulation of the diesel diluent.In addition, this will moderates the temperature of the bed for thishighly exothermic reaction by 1) dilution of the diesel feed, and 2) bytaking the product exiting the reactor beds to an external coolingsource such as a heat exchanger before it is returned back to thereactor. A schematic of the reactor configuration is shown below in FIG.2.

TABLE 2 EFFECT OF DIESEL TO SORBITOL RATIO ON SORBITOL CONVERSIONDiesel/Sorbitol ratio (vol) 2 3 4 Sorbitol Conversion 99.8 99.7 99.4Product Selectivity (C mol %) C1-C4 30.8 27.5 26.7 C5+ 66.9 70.5 71.3CO/CO₂ 2.3 1.9 2.0

The polyol feedstock injectors may be distributed at a variety ofintervals, either uniform in length or designed to increase or decreasepolyol concentrations over the length of the hydrotreating reactor. Inone embodiment the polyol feedstock injectors are distributed evenlyover the entire length of the reactor. The injectors may alsodistributed around the reactor to keep polyol concentrations uniformthroughout the entire reaction. In another embodiment polyol feedstockinjectors are distributed down the hydrotreating reactor with increasingfrequency, thus increasing polyol feedstock concentration down thelength of the reactor. By increasing the polyol concentration along thereactor, the reaction rate is also increased. In yet another embodiment,the polyol feedstock injectors are distributed with decreasingfrequency, injecting more polyol feedstock at the beginning of thereactor and less as the reaction increases in temperature. Thus as heatincreases along the interior of the hydrotreating reactor, the increasedspace between injectors decreases the reaction rate maintaining a coolertemperature while still generating more product.

TABLE 3 EFFECT OF DIESEL TO SORBITOL DILUTION RATIO ON REACTOR ΔPDiesel/Sorbitol ratio (vol) Pressure drop across reactor 2 ΔP wasobserved after about one week on stream operation at the temperature of640° F. due to coke formation on catalyst bed 4 No ΔP was observed afterone week on stream operation at 650° F. followed with 10 days operationat 680° F.

In closing, it should be noted that the discussion of any reference isnot an admission that it is prior art to the present invention,especially any reference that may have a publication date after thepriority date of this application. At the same time, each and everyclaim below is hereby incorporated into this detailed description orspecification as a additional embodiments of the present invention.

Although the systems and processes described herein have been describedin detail, it should be understood that various changes, substitutions,and alterations can be made without departing from the spirit and scopeof the invention as defined by the following claims. Those skilled inthe art may be able to study the preferred embodiments and identifyother ways to practice the invention that are not exactly as describedherein. It is the intent of the inventors that variations andequivalents of the invention are within the scope of the claims whilethe description, abstract and drawings are not to be used to limit thescope of the invention. The invention is specifically intended to be asbroad as the claims below and their equivalents.

REFERENCES

All of the references cited herein are expressly incorporated byreference. The discussion of any reference is not an admission that itis prior art to the present invention, especially any reference that mayhave a publication data after the priority date of this application.Incorporated references are listed again here for convenience:

-   1. U.S. Pat. Nos. 4,503,278, 4,549,031, “Process for converting    carbohydrates to hydrocarbons” Mobil Oil Corporation, Chen and    Koenig (1985).-   2. U.S. Pat. No. 5,959,167, WO9910450, “Process for conversion of    lignin to reformulated hydrocarbon gasoline” The University of Utah    Research Foundation (1985).-   3. U.S. Pat. No. 7,572,925, US2008033188, US2009124839,    WO2008151178, WO2008151178 “Production of Liquid Alkanes in the Jet    Fuel Range (C8-C15) from Biomass-Derived Carbohydrates,” Wisconsin    Alumni Res. Found., Dumesic and Roman-Leshkov, (2007).-   4. US2008173570, WO2008087269, Inst Francais du Petrole, Marchand    and Bertoncini, (2008)-   5. US2009126260, WO2009039015, WO2009039201, “Methods for Refining    Hydrocarbon Feedstocks” Sapphire Energy, Inc., Aravanis, et al.    (2009).-   6. WO2008114033 “BioGasoline” StatoilHydro ASA, Fredriksen and    Myrstad (2008).-   7. EP2034005, “Fuel additive concentrate derived from a biomass    resource” Furanix Tech. B.V, Gruter, (2009).-   8. U.S. Ser. No. 61/236,347, “HYDROTREATING CARBOHYDRATES,”    ConocoPhillips Co., Sughrue and Yao, (2009).-   9. David, et al., “A Review of Catalytic Issues and Process    Conditions for Renewable Hydrogen and Alkanes by Aqueous-Phase    Reforming of Oxygenated Hydrocarbons Over Supported Metal    Catalysts,” Appl. Catal. B., 56, 171 (2004)-   10. Huber, et al., “Renewable Alkanes by Aqueous-Phase Reforming of    Biomass-Derived Oxygenates” Angew. Chem. Int. Ed., 43, 1549 (2004)-   11. Metzger, “Production of Liquid Hydrocarbons from Biomass,”    Angew. Chem. Int. Ed., 45, 696 (2006)

The invention claimed is:
 1. A method of hydrotreating polyol feedstockthat reduces coking, the method comprising: a) contacting ahydrotreating catalyst with a diesel feedstock at the beginning of thereactor catalyst, b) contacting the hydrotreating catalyst with a polyolfeedstock at the beginning of the reactor catalyst, c) contacting thehydrotreating catalyst with one or more additional polyol feedstocks atintervals along the reactor catalyst, wherein said polyol feedstock isreacted on said catalyst to generate alkanes.
 2. The method of claim 1,wherein said fuel oil feedstock is heated to reaction temperature priorto contacting the hydrotreating catalyst.
 3. The method of claim 1,wherein said polyol feedstock comprises Glycol, Glycerol, Erythritol,Threitol, Arabitol, Ribitol, Xylitol, Allitol, Dulcitol, Galactitol,Iditol, Mannitol, Sorbitol, Isomalt, Lactitol, Maltitol, Trehalose, andcombinations thereof.
 4. The process of claim 1, wherein said fuel oilfeedstock is selected from the group consisting of gasoline, jet fuel,kerosene, heating oil, fuel oils, diesel fuel, petro-diesel, bio-diesel,synthetic diesel, blended diesel, and combinations thereof.
 5. Theprocess of claim 1,wherein said hydrotreating catalyst is selected fromthe group consisting of cobalt (Co), molybdenum (Mo), nickel (Ni),titanium (Ti), tungsten (W), zinc (Zn), antimony (Sb), bismuth (Bi),cerium (Ce), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr),manganese (Mn), rhenium (Re), iron (Fe), platinum (Pt), iridium (Ir),palladium (Pd), osmium (Os), rhodium (Rh), ruthenium (Ru), andcombinations thereof.
 6. The process of claim 1, wherein saidhydrotreating catalyst is a bimetallic catalyst selected from the groupconsisting of Co/Mo, Co/W, Ni/Mo, Ni/W, Ti/Mo, Ti/W and combinationsthereof.
 7. The process of claim 1, wherein said reaction occurs at anapproximate temperature of 400° F., 425° F., 450° F., 475° F., 500° F.,525° F., 550° F., 575° F., 600° F., 625° F., 650° F., 675° F., 700° F.,725° F., 750° F., 775° F., 800° F., 825° F., 850° F., 875° F., or 900°F.
 8. The process of claim 1, wherein said reaction occurs at anapproximate pressure of 500, 550, 600, 650, 700, 750, 800, 850, 900,950, 1000, 1050, 1100, 1150, 1200, 1250, 1500, 1750, 2000, 2250, 2500,2750, and 3000 psig.
 9. The process of claim 1, wherein saidhydrotreating catalyst is an unsupported catalyst selected from thegroup consisting of Co/Mo, Co/W, Ni/Mo, Ni/W, Ti/Mo, Ti/W, Co/Mo/W,Ni/Mo/W, Ti/Mo/W and combinations thereof.
 10. A method of hydrotreatingliquefied biomass feedstock that reduces coking, the method comprising:a) liquifying biomass to generate a polyol feedstock, b) contacting ahydrotreating catalyst with a fuel oil feedstock at the beginning of thereactor catalyst, c) contacting the hydrotreating catalyst with thepolyol feedstock at the beginning of the reactor catalyst, d) contactingthe hydrotreating catalyst with one or more additional polyol feedstocksat intervals along the reactor catalyst, wherein said polyol feedstockis reacted on said catalyst to generate alkanes.
 11. The method of claim10, wherein said fuel oil feedstock is heated to reaction temperatureprior to contacting the hydrotreating catalyst.
 12. The method of claim10, wherein said polyol feedstock comprises Glycol, Glycerol,Erythritol, Threitol, Arabitol, Ribitol, Xylitol, Allitol, Dulcitol,Galactitol, Iditol, Mannitol, Sorbitol, Isomalt, Lactitol, Maltitol,Trehalose, and combinations thereof.
 13. The process of claim 10,wherein said fuel oil feedstock is selected from the group consisting ofgasoline, jet fuel, kerosene, heating oil, fuel oils, diesel fuel,petro-diesel, bio-diesel, synthetic diesel, blended diesel, andcombinations thereof.
 14. The process of claim 10, wherein saidhydrotreating catalyst is selected from the group consisting of cobalt(Co), molybdenum (Mo), nickel (Ni), titanium (Ti), tungsten (W), zinc(Zn), antimony (Sb), bismuth (Bi), cerium (Ce), vanadium (V), niobium(Nb), tantalum (Ta), chromium (Cr), manganese (Mn), rhenium (Re), iron(Fe), platinum (Pt), iridium (Ir), palladium (Pd), osmium (Os), rhodium(Rh), ruthenium (Ru), and combinations thereof.
 15. The process of claim10, wherein said hydrotreating catalyst is a bimetallic catalystselected from the group consisting of Co/Mo, Co/W, Ni/Mo, Ni/W, Ti/Mo,Ti/W and combinations thereof.
 16. The process of claim 10, wherein saidreaction occurs at an approximate temperature of 400° F., 425° F., 450°F., 475° F., 500° F., 525° F., 550° F., 575° F., 600° F., 625° F., 650°F., 675° F., 700° F., 725° F., 750° F., 775° F., 800° F., 825° F., 850°F., 875° F., or 900° F.
 17. The process of claim 10, wherein saidreaction occurs at an approximate pressure of 500, 550, 600, 650, 700,750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1500, 1750,2000, 2250, 2500, 2750, and 3000 psig.
 18. The process of claim 10,wherein said hydrotreating catalyst is an unsupported catalyst selectedfrom the group consisting of Co/Mo, Co/W, Ni/Mo, Ni/W, Ti/Mo, Ti/W,Co/Mo/W, Ni/Mo/W, Ti/Mo/W and combinations thereof.